scholarly journals Study on the Rheological Behavior of a Model Clay Sediment

2021 ◽  
Vol 9 (1) ◽  
pp. 81
Author(s):  
Yuan Lin ◽  
Huaitao Qin ◽  
Jin Guo ◽  
Jiawang Chen

Clay sediments are the main component of seabed sediment. Interactions between the nano-sized, disk-shaped and charged clay particles are complicated, as they control the sediment’s rheology. In this study, we studied the rheological behavior of the clay sediment modeled by laponite and bentonite suspensions experimentally using a rotational rheometer. The yield stress decreased when water content increased. Meanwhile, the yield stress of the laponite suspension first increased and then decreased with increasing salinity. It is considered that the face-to-face repulsive electrostatic interaction between clay platelets dominated the yield behavior. A yield stress model was developed to describe the change of the yield stress with both the water content and the salinity. When the system started to flow, the viscosity decreased with increasing shear. A master curve of viscosity is was from the viscosity-stress curves at different water contents if the applied shear stress was normalized by the yield stress and the viscosity normalized by a characteristic viscosity. This study provides a preliminary understanding of the clay sediment rheology and its mechanism for the investigation on the flowing of the sediment systems with strong interparticle interaction.

2021 ◽  
Vol 2 (5) ◽  
pp. 352-357
Author(s):  
Azril N ◽  
Gareche M ◽  
Saoudi L ◽  
Zeraibi N

The effect of Polyethylene Oxide (PEO) with a molecular weight 10000g/mol on the rheological behavior of bentonite suspension was examined in terms of viscosity, yield stress and viscoelastic modulus (G’ and G’’); characteristic of complex behaviour of montmorillonite in water. A Physica MCR301 rheometer has been used to measure the rheological properties of samples (6% bentonite) as well as bentonite-PEO mixtures at different concentrations of PEO (0.18%, 0.25%, 0.5% and 1%). The polyethylene oxide adsorbs onto clay particles, which changes their basic characteristics depending on the amount of PEO adsorbed.


2018 ◽  
Vol 4 (4) ◽  
pp. 785 ◽  
Author(s):  
Wanjun Ye ◽  
Yuyu Zhang

This paper investigates the effect of dry-wet cycle process on the formation of loess slope spalling hazards. Based on the CT scan tests and macroscopic fissures analysis, the fissure variation law of loess samples under different dry-wet cycle times were determined. Through the laboratory direct shear tests, the variation law of shear strength, cohesion and angle of internal friction of loess samples under different dry-wet cycle times and different dry-wet cycle water content variation ranges were discussed. The results show that the natural water contents of Luo-chuan loess were higher than Tong-chuan loess due to it’s higher contents of clay particles. With the increase of dry-wet cycle times, the internal fissure numbers of loess samples increased dramatically. The value of shear strength and cohesion of loess samples in two different areas decreased dramatically due to the increase of dry-wet cycle times. Higher water content variation ranges of dry-wet cycles leaded to lower shear strength of loess samples under the same dry-wet cycle times. Loess slope spalling hazards often happened due to the decrease of shear strength and the occurrence of internal fissures in loess induced by the dry-wet cycle process.


2014 ◽  
Vol 23 (3) ◽  
pp. 132-139 ◽  
Author(s):  
Lauren Zubow ◽  
Richard Hurtig

Children with Rett Syndrome (RS) are reported to use multiple modalities to communicate although their intentionality is often questioned (Bartolotta, Zipp, Simpkins, & Glazewski, 2011; Hetzroni & Rubin, 2006; Sigafoos et al., 2000; Sigafoos, Woodyatt, Tuckeer, Roberts-Pennell, & Pittendreigh, 2000). This paper will present results of a study analyzing the unconventional vocalizations of a child with RS. The primary research question addresses the ability of familiar and unfamiliar listeners to interpret unconventional vocalizations as “yes” or “no” responses. This paper will also address the acoustic analysis and perceptual judgments of these vocalizations. Pre-recorded isolated vocalizations of “yes” and “no” were presented to 5 listeners (mother, father, 1 unfamiliar, and 2 familiar clinicians) and the listeners were asked to rate the vocalizations as either “yes” or “no.” The ratings were compared to the original identification made by the child's mother during the face-to-face interaction from which the samples were drawn. Findings of this study suggest, in this case, the child's vocalizations were intentional and could be interpreted by familiar and unfamiliar listeners as either “yes” or “no” without contextual or visual cues. The results suggest that communication partners should be trained to attend to eye-gaze and vocalizations to ensure the child's intended choice is accurately understood.


2013 ◽  
Vol 14 (3) ◽  
pp. 115-133
Author(s):  
조현 ◽  
Jaeshin Park ◽  
ki-jin jang

2008 ◽  
Vol 11 (4) ◽  
Author(s):  
Katrina A. Meyer

Thirteen students in a graduate-level course on Historical and Policy Perspectives in Higher Education held face-to-face and online discussions on five controversial topics: Diversity, Academic Freedom, Political Tolerance, Affirmative Action, and Gender. Students read materials on each topic and generated questions for discussion that were categorized by Bloom’s taxonomy so that the level of questions in the two discussion settings would be closely parallel. Upon completion of each discussion, they answered questions that addressed depth and length of the discussion, ability to remember, and a self-assessment of how the student learned. Students’ assessments show a consistent preference for the face-to-face discussion but a small number of students preferred the online setting. However, what is perhaps more interesting is a minority of approximately one-third of the students who perceived no difference between the settings, or that the two settings were perhaps complementary.


Trictrac ◽  
2018 ◽  
Vol 10 ◽  
Author(s):  
Petru Adrian Danciu

Starting from the cry of the seraphim in Isaiahʹ s prophecy, this article aims to follow the rhythm of the sacred harmony, transcending the symbols of the angelic world and of the divine names, to get to the face to face meeting between man and God, just as the seraphim, reflecting their existence, stand face to face. The finality of the sacred harmony is that, during the search for God inside the human being, He reveals Himself, which is the reason for the affirmation of “I Am that I Am.” Through its hypnotic cyclicality, the profane temporality has its own musicality. Its purpose is to incubate the unsuspected potencies of the beings “caught” in the material world. Due to the fact that it belongs to the aeonic time, the divine music will exceed in harmony the mechanical musicality of profane time, dilating and temporarily cancelling it. Isaiah is witness to such revelation offering access to the heavenly concert. He is witness to divine harmonies produced by two divine singers, whose musical history is presented in our article. The seraphim accompanied the chosen people after their exodus from Egypt. The cultic use of the trumpet is related to the characteristics and behaviour of the seraphim. The seraphic music does not belong to the Creator, but its lyrics speak about the presence of the Creator in two realities, a spiritual and a material one. Only the transcendence of the divine names that are sung/cried affirms a unique reality: God. The chant-cry is a divine invocation with a double aim. On the one hand, the angels and the people affirm God’s presence and call His name and, on the other, the Creator affirms His presence through the angels or in man, the one who is His image and His likeness. The divine music does not only create, it is also a means of communion, implementing the relation of man to God and, thus, God’s connection with man. It is a relation in which both filiation and paternity disappear inside the harmony of the mutual recognition produced by music, a reality much older than Adam’s language.


Author(s):  
Mary Cavanagh

The face to face interactions of reference librarians and reference assistants are studied from a theoretical practice perspective. Rather than reinforcing professional boundaries, the results of this analysis support reference practice in public libraries as a highly relational activity where reference “expertise” retains a significant subjectivist, relational dimension.Les interventions en personne des bibliothèques de référence et des adjoints à la référence sont étudiées du point de vue de la pratique théorique. Plutôt que de renforcer les frontières interprofessionnelles, les résultats de cette analyse appuient l'idée que les pratiques de référence en milieu public sont des activités hautement relationnelles où l'expertise de la référence conserve une dimension subjectiviste et relationnelle. 


Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  

IFLA Journal ◽  
2021 ◽  
pp. 034003522110182
Author(s):  
Evans F Wema

This article reviews literature on the use of virtual learning environments by highlighting their potential and the challenges of introducing the same in Tanzania. It introduces the concept of virtual learning environments by demonstrating their applications to support teaching and learning. The article discusses the use of virtual learning environments in teaching information literacy courses by highlighting the success of using such tools in facilitating the teaching of information literacy courses to library users. In this review, special emphasis is placed on attempts by Tanzanian institutions of higher learning to introduce web-based teaching of information literacy and the challenges faced. The review reveals the need for Tanzanian institutions of higher learning to develop virtual learning environments to facilitate the teaching of information literacy courses to students and faculty so as to reach many of those who may not manage to attend the face-to-face information literacy sessions that are offered by librarians on a regular basis.


2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii26-ii26
Author(s):  
Emma Toman ◽  
Claire Goddard ◽  
Frederick Berki ◽  
William Garratt ◽  
Teresa Scott ◽  
...  

Abstract INTRODUCTION Controversy exists as to whether telephone clinics are appropriate in neurosurgical-oncology. The COVID-19 pandemic forced neuro-oncology services worldwide to re-design and at the University Hospitals Birmingham UK, telephone clinics were quickly implemented in select patients to limit numbers of patients attending hospital. It was important to determine how these changes were perceived by patients. METHODS A 20-question patient satisfaction questionnaire was distributed to patients who attended neuro-oncology clinic in person (“face-to-face”), or via the telephone. Fisher’s exact test was used to determine significance, which was set at p< 0.05. RESULTS Eighty questionnaires were distributed between June 2020 and August 2020. Overall, 50% (n=40) of patients returned the questionnaire, 50% (n=23) of face-to-face and 50% (n=17) telephone patients. Of those who received telephone consultations, 88% (n=15) felt the consultation was convenient, 88% (n=15) were satisfied with their consultation and 18% (n=3) felt they would have preferred to have a face-to-face appointment. Of those who attended clinic in person, 96% (n=22) felt their consultation was convenient, 100% (n=23) were satisfied with their consultation and 13% (n=3) would have preferred a telephone consultation. Within the face-to-face clinic attendees, only 13% (n=3) were concerned regarding the COVID risk associated with attending hospital. There was no significant difference in patient convenience or satisfaction (p=0.565 and p=0.174 respectively) between face-to-face and telephone clinics. There was no significant difference in whether patients would’ve preferred the alternative method of consultation (p > 0.999). CONCLUSION Our study suggests that careful patient selection for neuro-oncology telephone clinic is not inferior to face-to-face clinic. Telephone clinic during COVID-19 pandemic proved to be convenient, safe and effective. This global health crisis has transformed telephone neuro-oncology consultations from an experimental innovation into established practice and should be continued beyond the pandemic in select cases.


Sign in / Sign up

Export Citation Format

Share Document